Suction dredge relief valve system



Oct. 23, 1951 ER 2,572,263

SUCTION DREDGE RELIEF VALVE SYSTEM Filed May 2, 1949 MAST R SWITCH [loch-o ac fua fed DEF/N/TE.

TIME

RELAYSWITCH SSEOX? IIIISSIHI INVENTOR m BY ATTO R N EYS Patented Oct. 23, 1951 UN l TED "S PAT EN T OF F I CE 2,572,263 'JS'UCTIONDREDGE RELIEF VALVE SYSTEM David LJHofer, Berkeley, Calif. Application May 2, 1949, Serial No. "90,809

14 Claims.

This invention relates generally to a safety system for suctiondredgsithe'system being automatically operative to. "relieve eicssive vacuum in the suction pipe i'esulting nomiem gm'g of the intake end thereof, and to correct velocity drop in the discharge pipe resulting "from overloading thereof with material, I

The present invention I, is 'a iiiddifi'catidh 'of the system shown in;cpendiiig mutation, Serial No. 783,738, filedNovember 3, "1947.

-0ne object of this invention is to provide "a normally closed, safety relief valve unit inc omv munication with the suction pipe of the dredge adapted 'to freely feed water thereto to relieve said plugging; the safety valve unit being mounted in connect-ion with said suction pipe above water, as close to thesuction pump on the dredge as possible, and witha minimum of passageibetween'the valve and the interior offsaid suction pipe. It hasbeenfoundthat the application of a free flow of water into the suction pipe at a point very close to the suction pump produces the best results with'respect to freeing of a plug at the lowerendof the-suction pipe; the column of water and materialinthe-suction pipe above the plug tending to free the latter when the safety relief valve unit is openedandmo material'suction is being imposed'on said column.

Another object is to provide a novel control system for the safety "relief valve unit; said system including a normally energized=electro-actu ated device operative to hold the safety relief valve unit closed, and a mechanical device, such as a weight, ODGIatiVE WhED the electro-actuated'de'vice is deenergized-to quickly and 'automatically open said safety relief valve unit. This is important,'as positive'opening of the valve unit is assured, even in the event of electric power failure.

A further object of this: invention is to provide a relief valve system, for the purpose described, which ismountedentirelyonthe dredge, thus being readilyand conveniently-accessible for maintenance "and repair.

It is also an'ob'jec t of the invention to provide -aifelief valve system which includes a-novel cont'r'o'l circuit, responsive to abnormal conditions yin-'b'oth the'suction and discharge pipes, to cause the safety relief valve unit 'to :open.

A further object of "the invention is to provide a practical and reliable relief valve system, and one which will 'be exceedingly 'effective for the purpose for which it is designed. I These objects are accomplished 'by means of such structure and relative arrangement'of parts as will fully appear by api'usal of 'the following specification and clalirr'is.

'The figure of the drawing is *a somewhat diagrammatic side elevation of the safety relief valve unites mountedpn a dredge; the'control "circuit being shown diagrammatically in "connectier-1 therewith.

Referring now more particularly to the char-- acters of reference on the drawing, the system is adapted, for use in connection with a suction dredge which includes a barge, indicated generally at I, having a power driven, heavy 'duty dredge 'fpu'm 2 mounted thereon.

A suction pipe '3 leads from the'pu'm'p intake "'4 to an under-water point for dredge pick-up, and s'aidsuction pipe '3 includes a fleiiible portion 5 to permit of the'necessary'inovements'of the intake end of said pipe.

I A discharge pipe 6 leads from thedredge'pump 2, and itis through this pipe that the dredged materialis delivered from the dredge barge I.

The novel relief valve System comprises the following: o A

-A relief valve unit, indicated generally at I, "is coupled, "as at 8, to the suction pipe 3, on top of the latter, an'da's close to the pump intake"! as is mechanically convenient; said "relief valve unit 7 also being disposed so'that a minimum of passage eii'tnds between said unit and the interior offthe "suction pipe 3. l I

Thereliefvalve unit '1 includes therein a"norinally closed butterfly valve'9, mounted on'a'cro's's shaft To which eirte'nds out of 'theunit "I'through suitable seals. r

A radial ever II 'is fixed on one'exter'ior end teitionbr the cross shaft '10, and normally pro- Jects generally horizontally. This radial lever H is scrawny in fa raised position, at which time the"liiitt'erfly valve 9 'i'sclosed; the lever ll being Held 'insu'ch raised position by a normallyenef- 'g'ized'electro-actuator [2 including a plunger 13 eenheeteate the radial lever II by "a link The electro a ctuator T2 is norinally'energized by a 'circuitarrangernent hereinafter described, and upon deenergi zation of said actuator the plunger l3, link [4, and radial lever 'l'l sw'lri'g downwardly to open the butterfly valve 9. This dpen'in'g inotionis causedby a mechanical device, siic'h as "a 'weight 15, suspended from the radial lever II by a link [6. The weight l5thu'salw ays tends to open the butterfly valve '9, but under normal conditions is prevented from doing so by the energized electro-actuator l2.

The'controlor regulating circu'itof theinven' tion comprises the following:

The normally energized electro actuator 12 is connected to a three pha'se main,'current supply "I? having a normally closed electro-actuated master switch "3 therein; said master switch being connected-and responsive to a control circuit, indicated generally at l 9 the latter-including-one lead 2!! and another lead 2|.

Thecontrol circuit 19 is connected, at the end opposite the master switch, to "a normally closed, low pressure responsive switch 22 coupled by a "conduit 23 to the discharge pipe 6. A normally open hand valve ZQ-is interposed-in the conduit 23 The lead '20 of the control circuit l5 has a definite time relay -25 interposed therein, the

switch of such relay being normally closed, but adapted to be opened for a predetermined, limited time upon energization of the relay. Such definite time relay 25 is under the regulation of a control circuit 26, and energizing current for said relay is supplied through a sub-circuit 21 which leads from the main current supply circuit ll ahead of the master switch 18.

The relay control circuit 26 connects, at the end opposite said relay 25, with a normally open, excess vacuum responsive switch 28; the latter being of a type which is adjustable to respond at a selected vacuum. The excess vacuum responsive switch 28 is connected by a conduit 29 to the suction pipe 3 very close to the pump intake 4; there being a normally open hand valve 30 in the conduit 29.

A normally closed, manual switch 3| is interposed in the other lead 2| of the control circuit I9.

When the dredge is operating under conditions of normal vacuum in the suction pipe 3, and normal pressure in the discharge pipe 6, the relief valve I is closed.

Upon the suction pipe 3 becoming clogged or plugged at its intake end, with resultant creation of excessive and dangerous vacuum in the suction pipe 3, the excess vacuum res onsive switch 28 closes the relay control switch 26. When this occurs the relay 25opens for a definite period of time, breaking the control circuit l9 and resu ting in opening of the master switch Hi.

When the master switch 18 is opened, the electro-actuator I2 is deenergized, its plun er falls, and the weight i5 immediately opens the butterfly valve 9. The instant that the butterfly valve 9 o ens, free-flowing, excess vacuum relief water feeds into the suction pipe 3 ad acent the pump intake 4 from a water intake pipe which leads from below water to connection with the upper end of the relief valve unit 'I' by means including an elbow 33.

As such free flowing water surges into the suction pipe 3, with resultant relief of excessive vacuum therein, the plug at the lower end of the suction pipe 3 is relieved. This relief is due in part to the column of water and dredged material in the downwardly inclined suction pipe 3 above the plug. It is extremely advantageous that the excess vacuum relief water be fed into the suction pipe 3 as close to the pump intake 4 as possible. This is for the reason that the closer circuit I9, with resultant opening of the master switch l8. Here again the opening of the master switch results in immediate opening of the relief valve unit I, whereupon free flowing water feeds into the suction pipe 3 closely adjacent the pump intake 4, which water, as it passes through the pump 2 and into the discharge pipe 6, relieves the over-loading in the latter, so that the velocity of the discharge may be increased and normal conditions re-established.

As soon as such normal conditions re-establis'n, the switch 22 returns to its normally closed position, resulting in closing of the master switch 18, and responsive closing of the relief valve unit I.

The described system is a practical, effective, and reliable one for the automatic relief of dangerous operating conditions occurring in the pumping assembly of a suction dredge, including the suction pipe, the discharge pipe, and the pump interposed therebetween.

As the relief valve unit is above water, and

on the barge l, and not on the suction pipe 3 adjacent its under-water intake end as before, it is not subject to possible interference by caveins, etc.

Additionally, said relief valve unit I and the controls therefore are readily accessible for maintenance and repair.

If, for any reason, the dredge operator desires to open the relief valve unit I under conditions where its opening is not automatic, the manual switch 3| is opened, which breaks the control circuit l9 and causes opening of the master switch I8, as previously described.

From the foregoing description it will be readily seen that there has been produced such a system as substantially fulfills the objects of the invention as set forth herein.

While this specification sets forth in detail the presentand preferred construction of such system, still in practice such deviations therefrom may be resorted to as do not form a departure from the spirit of the invention, as defined by the appended claims.

Having thus described the invention, the fol-, lowing is claimed as new and useful, and upon which Letters Patent are desired:

the point of relief to the pump 2, the lesser the likelihood of damage to the latter u on occurrence of vacuum in said suction pipe 3.

After passing of the predetermined definite time, the relay 25 returns to its normally closed position, whereupon the master switch [8 closes and all the parts return to their normal position; assuming, of course, that the plug at the lower end of the suction pipe 3 cleared during said time interval. Otherwise, the safety system will repeat the opening of the relief valve unit I for another time interval.

Another condition of danger which sometimes occurs, either by improper control by the dredge operator or due to working conditions, is loss of velocity in the discharge pipe 6, with resulting over-loading thereof; this resulting in a pressure drop in said discharge pipe.

The system automatically functions to prevent damage under these circumstances, as follows:

Upon a dangerous pressure drop in the discharge pipe 6, the normally closed, low pressure responsive switch 22 opens, breaking the control 1. In combination, on a dredge, of a pump, a suction pipe leading to the intake of the pump. and a discharge pipe extending from the outlet of the pump; a relief valve system comprising a normally closed safety relief valve unit mounted in communication with the suction pipe above water, a water intake pipe leading from below water adjacent the dredge to said valve unit, and means responsive to excess vacuum in the suction pipe operative to open'said valve unit.

2. In combination, on a dredge, of a pump, a suction pipe leading to the intake of the pump, and a discharge pipe extending from the outlet of the pump; a relief valve system comprising a normally closed safety relief valve unit mounted in communication with the suction pipe above water, a water intake pipe leading from below water adjacent the dredge to said valve unit, and means responsive to excess vacuum in the suction pipe operative to open said valve unit; the valve unit communicating with the suction pipe close to the intake of the pump.

3. In combination, on a dredge, of a pump, a suction pipe leading to the intake of the pump, and a, discharge pipe extending from the outlet of the pump; a relief valve system comprising a normally closed safety relief valve unit mounted in communication with the suction pipe above water, a water intake pipe leading from below water adjacent the dredge to said valve unit, and means responsive to excess vacuum in the suction pipe operative to open said valve unit; the valve unit communicating with the suction pipe close to the intake of the pump, and there being only a short flow passage between the valve unit and the interior of said suction pipe.

4. A system, as in claim 3, in which the valve unit is on top of the suction pipe.

5. A system, as in claim 4, in Which the water intake pipe couples to the valve unit from above.

6. In combination, on a dredge, of a pump, a suction pipe leading to the intake of the pump, and a discharge pipe extending from the outlet of the pump; a relief valve system comprising a normally closed safety relief Valve unit mounted in communication with the suction pipe above water, a water intake pipe leading from below water adjacent the dredge to said valve unit, a mechanical device connected to the valve unit tending at all times to open the same, a normally energized electro-actuator connected to the valve unit normally holding the latter closed in opposition to said mechanical device, and means responsive to excess vacuum in the suction pipe operative to deenergize said electro-actuator whereby the mechanical device then opens the valve unit.

7. In combination, on a dredge, of a pump, a suction pipe leading to the intake of the pump, and a discharge pipe extending from the outlet of the pump; a relief valve system comprising a normally closed safety relief valve unit mounted in communication with the suction pipe above water, a water intake pipe leading from below Water adjacent the dredge to said valve unit, a mechanical device connected to the valve unit tending at all times to open the same, a normally energized electro-actuator connected to the valve unit normally holding the latter closed in opposition to said mechanical device, and means responsive to excess vacuum in the suction pipe operative to deenergize said electro-actuator whereby the mechanical device then opens the valve unit; said mechanical device including a weight movable downward to open the valve unit.

8. In combination, on a dredge, of a pump, a suction pipe leading to the intake of the pump; a relief valve system comprising a normally closed safety relief valve unit mounted in communication with the suction pipe above water, a water intake pipe leading from below water adjacent the dredge to said valve unit, a mechanical device connected to the valve unit tending at all times to open th same, a normally energized electro-actuator connected to the valve unit normally holding the latter closed in opposition to said mechanical device, a control circuit for said electro-actuator, and means responsive to excess vacuum in the suction pipe or low pressure in the discharge pipe operative to cause the control circuit to function in a manner to deenergize the electro-actuator whereby the mechanical device then opens the valve unit.

9. In combination, on a dredge, of a pump, a suction pipe leading to the intake of the pump; a relief valve system comprising a normally closed safety relief valve unit mounted in communication with the suction pipe above water, a water intake pipe leading from below water adjacent the dredge to said valve unit, a mechanical device connected to the valve unit tending at all times to open the same, a normally energized electro-actuator connected tothe valve unit normally holding the latter closed in opposition to said mechanical device, a control circuit for said electro-actuator, and means responsive to excess vacuum in the suction pipe or low pressure in the discharge pipe operative to cause the control circuit to function in a manner to deenergize the electro-actuator whereby the mechanical device then opens the valve unit; said means including an excess vacuum responsive switch in communication with the suction pipe, and a low pressure responsive switch in communication with the discharge pipe.

10. In combination, on a dredge, of a pump, a suction pipe leading to the intake of the pump, and a discharge pipe extending from the outlet of the pump; a relief valve system comprising a normally closed safety relief valve unit mounted in communication with the suction pipe above water and adjacent the pump, said valve unit including a normally closed butterfly valve and a projecting valve supporting shaft, a radial lever on said shaft, a weight suspending from the lever always tending to lower the same and open the valve, a normally energized electro-actuator connected to the valve unit normally holding the latter closed in opposition to said weight, and

means responsive to abnormal conditions of vacuum and pressure in the suction and discharge pipes, respectively, operative to deenergize the electro-actuator whereby the weight opens the valve unit.

11. In the combination, on a dredge, of a pump, a suction pipe leading to the intake of the pump, and a discharge pipe extending from the outlet of the pump; a relief valve system comprising a normally closed. safety relief valve unit mounted in communication with the suction pipe, said safety relief valve unit being arranged, when open, to deliver water to the suction pipe above its lower end, and means responsive to abnormal pumping pressure conditions in at least one of the pipes operative to open said safety relief valve unit.

12. In the combination, on a dredge, of a pump, a suction pipe leading from below water to the intake of the pump, and a discharge pipe extending from the outlet of the pump; a relief valve system comprising a relief valve connected in communication with the suction pipe, said relief valve being arranged, when open, to deliver water into the suction pipe above its lower end, self-acting mechanical means connected to and tending to open the relief valve, and releasable power means resisting said mechanical means and normally holding the relief valve closed.

13. A relief valve system, as in claim 12, in which said mechanical means is a gravity displaced weight.

14. In the combination, on a dredge, of a pump, a suction pipe leading from below water to the intake of the pump, and a discharge pipe extending from the outlet of the pump; a relief valve system comprising a relief valve connected in communication with the suction pipe, said relief valve being arranged, when open, to deliver water into the suction pipe above its lower end, selfacting mechanical means connected to and tending to open the relief valve, and releasable power means resisting said mechanical means and normally holding the relief valve closed; said power means being automatically releasable in response to abnormal pumping pressure conditions in at least one of the pipes.

DAVID L. HOFER.

No references cited. 

